Is SAD a Northern Hemisphere Phenomenon? Does It Happen To People in the Southern Hemisphere?

While summer is fast approaching in the US, Canada, Europe, and the rest of the Northern Hemisphere, the other half of the globe is entering its colder, darker months. And with less sunlight means more risk of being sad and getting SAD, also known as Seasonal Affective Disorder.

SAD was first named in the early 1980s and has become widely accepted as a seasonal mood disorder that is a form of depression. The condition may be a remnant of the common animal pattern of hibernating during the cold months. Low temperatures, low mood, and low activity just go together.

In the morning, exposure to 20-30 minutes of daylight (not necessarily sunlight) is a great way to combat SAD. If that is not possible, the first treatment for SAD that is listed by the Mayo Clinic is light therapy. While sitting in front of a $60 light box for 20 minutes a day was popular a few years ago, the general lighting industry caught up and has been marketing full spectrum and daylight bulbs to address a lack of natural daylight.

An example of a full spectrum fluorescent light bulb.

The source of the daylight is not the trick, rather it is getting at least 10,000 lux for 30 minutes per day. While a light box can do this, so can any light bulb that produces strong blue spectrum wavelengths. Any light bulb marketed as “full spectrum” or “daylight” will usually meet this requirement.

If you’re familiar with our lessons on color temperature, you will recall that daylight color temperature at noon is 5600K. Therefore, any light bulb with a color temperature of 5000K or higher meets the standard for helping with SAD.

One myth about SAD and light therapy is that neodymium bulbs are an effective treatment. While incandescent bulbs are 2700K, manufacturers make bulbs coated with neodymium, which filter out yellow light, resulting in a light that is whiter and therefore mimics daylight. However, this is not exactly the same as using a full spectrum bulb, or getting actual sunlight. Neodymium bulbs, because they are incandescent, are cheaper than actual full spectrum bulbs but have not been shown to treat seasonal affective disorder. If you do want to try them, GE Reveal is one popular brand of neodymium bulbs.

One of the more interesting aspects of light therapy in regards to treating seasonal affective disorder is that, according to the Can-SAD Study, “Light treatment showed earlier response onset and lower rate of some adverse events relative to fluoxetine, but there were no other significant differences in outcome between light therapy and antidepressant medication.” Take an expensive pill, or change a light bulb.

So, if you’re enjoying your summer with a vacation to sub-Saharan Africa or South America, and all the natives seem a little down, don’t blame it on them. Remember, it’s winter in their tropical paradise. Just hand them a daylight bulb.